1. Field of the Invention
The present invention generally relates to circuitry for protection of data stored within volatile devices, and more specifically, relates to circuitry capable of reacting to a fast negative transition of a supply level from a primary power source for initiating a switchover from the primary power source to a secondary power source.
2. Description of the Related Art
Volatile devices require power to maintain stored data. If power is removed from the volatile devices, the stored data is lost. Such volatile devices include volatile memory, clocks, and any other device that will lose the data upon the loss of power.
Conventional systems generally contain power source switchover circuitry for detecting that a supply level from a primary power source decreases below a threshold voltage and for initiating a switchover to a secondary or backup power source. The switchover to the secondary power source maintains power to the volatile elements to avoid loss of the stored data. However, the power source switchover circuitry utilized to switch from the primary power source to the secondary power source in conventional systems is designed to be stable over temperature and process corners, and not designed to respond to a fast ramp-down or negative transition of the supply level of the primary power source.
System designers have recently been interested in designing systems capable of performing a fast ramp-down of the primary power source. This presents a problem as the power source switchover circuitry in conventional systems cannot initiate a switchover from the primary source to the secondary power source for a fast ramp-down of the supply level of the primary power source (i.e., the fast ramp-down of the supply level is not detected by the power source switchover circuitry).